Stacked display panels for image enhancement

ABSTRACT

A head-mounted display (HMD) includes an electronic display element and an optics block. The electronic display element includes a plurality of display panels that together output image light. The plurality of panels including a first display panel and a second display panel. The first display panel includes a first plurality of sub-pixels that are separated from each other by a non-emission area. The second panel includes a second plurality of sub-pixels. The second display panel is positioned offset from the first display panel such that the second plurality of sub-pixels emit light through the non-emission area of the first display panel. The optics block configured to direct the image light to an exit pupil of the HMD corresponding to a location of an eye of a user of the HMD.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of prior co-pending U.S. ProvisionalPatent Application No. 62/162,931, filed May 18, 2015, the disclosure ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure generally relates to enhancing images fromelectronic displays, and specifically to using stacked display panelsfor image enhancement.

Electronic displays include a plurality of pixels, which may eachinclude a plurality of sub-pixels (e.g., a red sub-pixel, a greensub-pixel, etc.). Arrangement of individual sub-pixels may affect theappearance and performance of an electronic display device. A sub-pixelincludes both an emission area and a non-emission area, and the fillfactor of the sub-pixel describes the ratio of light emission areaversus total area of the sub-pixel. The non-emission areas thus limitthe fill factor of each sub-pixel. Additionally, some arrangements ofsub-pixels may increase fixed pattern noise under certain conditions.For example, magnification of a pixel may result in non-emission areasbetween individual sub-pixels of the pixel becoming visible to the user,resulting in a “screen door” pattern (i.e., an increase in fixed patternnoise) in an image presented to a user.

SUMMARY

A stacked electronic display element includes a plurality of displaypanels that together output image light. The plurality of panelsincluding a first display panel and a second display panel. The firstdisplay panel includes a first plurality of sub-pixels that areseparated from each other by a non-emission area. The second displaypanel includes a second plurality of sub-pixels. The second displaypanel is positioned offset from the first display panel such that thesecond plurality of sub-pixels emit light through the non-emission areaof the first display panel. The stacked electronic display element maybe used to, e.g., increase effective fill factor, increase resolution,present high dynamic range images, present three dimensional images, orsome combination thereof.

In some embodiments, the stacked electronic display is part of ahead-mounted display. The HMD includes an optics block configured todirect the image light to an exit pupil of the HMD corresponding to alocation of an eye of a user of the HMD.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system environment including a virtualreality system, in accordance with an embodiment.

FIG. 2A is a diagram of a virtual reality headset, in accordance with anembodiment.

FIG. 2B is a cross section of a front rigid body of the VR headset inFIG. 2A, in accordance with an embodiment.

FIG. 3 is an example stacked electronic display element including twodisplay panels, in accordance with an embodiment

FIG. 4A is an example array of sub-pixel emission areas on a frontelectronic display panel of a stacked electronic display element.

FIG. 4B is an example array of aggregate sub-pixel emission areas on astacked electronic display panel.

FIG. 5 is an example array of aggregate sub-pixel emission areas on astacked electronic display element configured to operate as a highdynamic range display.

FIG. 6A is a perspective view of an example 3D image object, accordingto an embodiment.

FIG. 6B is a cross section of the 3D image object in FIG. 6A, accordingto an embodiment.

FIG. 6C is a diagram including a stacked electronic display elementconfigured to operate as a 3D display, according to an embodiment.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles, or benefits touted, of the disclosure described herein.

DETAILED DESCRIPTION

System Overview

FIG. 1 is a block diagram of a virtual reality (VR) system environment100 in which a VR console 110 operates. The system environment 100 shownby FIG. 1 comprises a VR headset 105, an imaging device 135, and a VRinput interface 140 that are each coupled to the VR console 110. WhileFIG. 1 shows an example system 100 including one VR headset 105, oneimaging device 135, and one VR input interface 140, in other embodimentsany number of these components may be included in the system 100. Forexample, there may be multiple VR headsets 105 each having an associatedVR input interface 140 and being monitored by one or more imagingdevices 135, with each VR headset 105, VR input interface 140, andimaging devices 135 communicating with the VR console 110. Inalternative configurations, different and/or additional components maybe included in the system environment 100.

The VR headset 105 is a head-mounted display that presents media to auser. Examples of media presented by the VR head set include one or moreimages, video, audio, or some combination thereof. In some embodiments,audio is presented via an external device (e.g., speakers and/orheadphones) that receives audio information from the VR headset 105, theVR console 110, or both, and presents audio data based on the audioinformation. An embodiment of the VR headset 105 is further describedbelow in conjunction with FIGS. 2A and 2B. The VR headset 105 maycomprise one or more rigid bodies, which may be rigidly or non-rigidlycoupled to each other together. A rigid coupling between rigid bodiescauses the coupled rigid bodies to act as a single rigid entity. Incontrast, a non-rigid coupling between rigid bodies allows the rigidbodies to move relative to each other.

The VR headset 105 includes an electronic display 115, an optics block118, one or more locators 120, one or more position sensors 125, and aninertial measurement unit (IMU) 130. The electronic display 115 displaysimages to the user in accordance with data received from the VR console110. In various embodiments, the electronic display 115 may comprise asingle stacked electronic display element or multiple stacked electronicdisplay elements (e.g., a stacked electronic display element for eacheye of a user).

A stacked electronic display element is a plurality of display panelsthat together output image light. As discussed in detail below, astacked electronic display element may be used to enhance images in aplurality of ways (e.g., increase effective fill factor, increaseresolution, present high dynamic range images, present three dimensionalimages, or some combination thereof). The stacked electronic displayelement includes at least a front display panel and a rear displaypanel, and in some embodiments may be separated by one or moreintermediate components. The front display panel is a transparentelectronic display panel. A transparent electronic display panel ispartially or fully transparent and may be, for example, a transparentorganic light emitting diode display (TOLED), some other transparentelectronic display, or some combination thereof. An intermediatecomponent may be a transparent electronic display panel, a film (e.g.,attenuator, polarizer, diffractive, spectral, etc.), or some combinationthereof. The rear display panel may be, e.g., a liquid crystal display(LCD), an organic light emitting diode (OLED) display, an active-matrixorganic light-emitting diode display (AMOLED), a TOLED, some otherdisplay, or some combination thereof.

The display panels are stacked such that image light emitted from therear display panel passes through any intermediate components and thefront display toward the optics block 118. Likewise any intermediatecomponent that is a transparent electronic display panel emits imagelight that passes through the front display panel toward the opticsblock, and may additionally pass through other intermediate componentsprior entering the front display panel.

Each display panel in a stacked electronic display element includes adisplay area comprising a plurality of sub-pixels (e.g., transparentOLED (TOLED)), where a sub-pixel is a discrete light emitting componentthat is positioned in the emission layer. For example, a sub-pixel emitsred light, yellow light, blue light, green light, white light, or anyother suitable color of light. A sub-pixel includes both an emissionarea, and a non-emission area, and a fill factor of the sub-pixeldescribes the ratio of light emission area versus total area of thesub-pixel.

It is desirable to have a high fill factor as it reduces fixed patternnoise in a display area. The display area is a portion of the electronicdisplay panel that is presented to the viewing user. As shown below withreference to FIG. 4A, the emission area is an area of the sub-pixelwhich emits light. The non-emission area is an area of the sub-pixelwhich does not emit light, and generally includes transistors,electrodes, etc., which belong to the structure of an electronic displaypanel and are not active emitters of light. Different sub-pixels areseparated from each other by the non-emission areas (also referred to asdark spaces) of adjacent sub-pixels.

In some embodiments, the display panels in the stacked electronicdisplay element are positioned such that there is no, negligible, orminimal overlap between emissions areas of different display panels. Forexample, the emission areas of a first electronic display panel thatemits image light into an input surface of a second electronic displaypanel backfills some, or all of, the non-emission areas of the secondelectronic display panel with light emitted from the first electronicdisplay panel. Accordingly, an effective area of emitted light relativeto the total area of the sub-pixel is increased. This increases aneffective fill factor of the stacked electronic display element andthereby reduces the screen door effect. An effective fill factor is afill factor based on the aggregate emissions areas and non-emissionareas of the electronic display panels in the stacked electronic displayelement. Accordingly, in the above manner, a stacked electronic displayelement results in a higher fill factor than conventional electronicdisplays, as discussed in detail below with regard to FIGS. 4A and 4B.

Moreover, in some embodiments, the stacked electronic display elementhas a higher resolution than a single electronic display element. Forexample, different signals may be provided to each of the electronicdisplay panels in the stacked electronic display element in order toproduce an aggregate image that has a higher resolution than an imageproduced by a single electronic display panel. An aggregate image is animage composed of image light emitted from different electronic displayelements in the stacked electronic display element.

In some embodiments, the stacked electronic display element isconfigured to emit high dynamic range (HDR) images. The stackedelectronic display element may be configured such that each electronicdisplay panel within the stacked electronic display element outputsimage light at different dynamic ranges, such that an aggregate imageemitted by the stacked electronic display panel is a high dynamic range(HDR) image. For example, the front electronic display panel may beconfigured to drive the higher dynamic range of an image and the rearelectronic display panel could drive the lower dynamic range of theimage, resulting in an aggregate image that is an HDR image.Accordingly, in the above manner, a stacked electronic display may beconfigured to operate as a HDR display, as discussed in detail belowwith regard to FIGS. 5A and 5B.

In some embodiments, the stacked electronic display element isconfigured to emit three dimensional (3D) images. A typical electronicdisplay emits images in two dimensions (e.g., x and y components in aCartesian coordinate system), however, in contrast a 3D image alsoincludes depth (e.g., a z component). The stacked electronic displayelement segments a total depth of a 3D image into different regions andassigns each segment to a different electronic display panel within thestacked electronic display element. As the electronic display elementsare located at different positions in the stacked electronic displayelement, and emit image light corresponding to their assigned segment,the aggregate image emitted by the stacked electronic display element isa 3D image. Accordingly, in the above manner, a stacked electronicdisplay may be configured to operate as a 3D display, as discussed indetail below with regard to FIGS. 6A-6C.

In some embodiments, images projected by the electronic display 115 arerendered on the sub-pixel level. This is distinct from, say an RGB(red-green-blue) layout, which has discrete red, green, and blue pixels(red, green, and blue) and each pixel in the RGB layout includes a redsub-pixel, which is adjacent to a green sub-pixel that is adjacent to ablue sub-pixel. The red, green, and blue sub-pixels operate together toform different colors. In an RGB layout a sub-pixel in a pixel isrestricted to working within that pixel. However, in some embodiments,sub-pixels in the electronic display operate within multiple “logical”pixels in their surrounding vicinity to form different colors. Thesub-pixels are arranged on the display area of the electronic display115 in a sub-pixel array. Examples of a sub-pixel array include PENTILE®RGBG, PENTILE® RGBW, some another suitable arrangement of sub-pixelsthat renders images at the sub-pixel level.

The optics block 118 magnifies received light from the electronicdisplay 115, corrects optical errors associated with the image light,and the corrected image light is presented to a user of the VR headset105. An optical element may be an aperture, a Fresnel lens, a convexlens, a concave lens, a filter, or any other suitable optical elementthat affects the image light emitted from the electronic display 115.Moreover, the optics block 118 may include combinations of differentoptical elements. In some embodiments, one or more of the opticalelements in the optics block 118 may have one or more coatings, such asanti-reflective coatings.

Magnification of the image light by the optics block 118 allows theelectronic display 115 to be physically smaller, weigh less, and consumeless power than larger displays. Additionally, magnification mayincrease a field of view of the displayed media. For example, the fieldof view of the displayed media is such that the displayed media ispresented using almost all (e.g., 110 degrees diagonal), and in somecases all, of the user's field of view. Magnification of the image lightmay cause an increase in fixed pattern noise, also referred to as the“screen door effect,” which is a visual artifact where dark spaceseparating pixels and/or sub-pixels of a display become visible to auser in an image presented by the display. However, as noted above, thestacked electronic display element in the electronic display 115 may beconfigured to such that electronic display panels backfill the darkspaces (non-emission areas) of other electronic display panels, thusreducing the screen door effect. In some embodiments, the dark spacescan effectively be reduced to zero. In some embodiments, the opticsblock 118 is designed so its effective focal length is larger than thespacing to the electronic display 115, which magnifies the image lightprojected by the electronic display 115. Additionally, in someembodiments, the amount of magnification may be adjusted by adding orremoving optical elements.

The optics block 118 may be designed to correct one or more types ofoptical error. Examples of optical error include: two dimensionaloptical errors, three dimensional optical errors, or some combinationthereof. Two dimensional errors are optical aberrations that occur intwo dimensions. Example types of two dimensional errors include: barreldistortion, pincushion distortion, longitudinal chromatic aberration,transverse chromatic aberration, or any other type of two-dimensionaloptical error. Three dimensional errors are optical errors that occur inthree dimensions. Example types of three dimensional errors includespherical aberration, comatic aberration, field curvature, astigmatism,or any other type of three-dimensional optical error. In someembodiments, content provided to the electronic display 115 for displayis pre-distorted, and the optics block 118 corrects the distortion whenit receives image light from the electronic display 115 generated basedon the content.

The locators 120 are objects located in specific positions on the VRheadset 105 relative to one another and relative to a specific referencepoint on the VR headset 105. A locator 120 may be a light emitting diode(LED), a corner cube reflector, a reflective marker, a type of lightsource that contrasts with an environment in which the VR headset 105operates, or some combination thereof. In embodiments where the locators120 are active (i.e., an LED or other type of light emitting device),the locators 120 may emit light in the visible band (˜380 nm to 750 nm),in the infrared (IR) band (˜750 nm to 1 mm), in the ultraviolet band (10nm to 380 nm), some other portion of the electromagnetic spectrum, orsome combination thereof.

In some embodiments, the locators 120 are located beneath an outersurface of the VR headset 105, which is transparent to the wavelengthsof light emitted or reflected by the locators 120 or is thin enough notto substantially attenuate the wavelengths of light emitted or reflectedby the locators 120. Additionally, in some embodiments, the outersurface or other portions of the VR headset 105 are opaque in thevisible band of wavelengths of light. Thus, the locators 120 may emitlight in the IR band under an outer surface that is transparent in theIR band but opaque in the visible band.

The IMU 130 is an electronic device that generates fast calibration databased on measurement signals received from one or more of the positionsensors 125. A position sensor 125 generates one or more measurementsignals in response to motion of the VR headset 105. Examples ofposition sensors 125 include: one or more accelerometers, one or moregyroscopes, one or more magnetometers, another suitable type of sensorthat detects motion, a type of sensor used for error correction of theIMU 130, or some combination thereof. The position sensors 125 may belocated external to the IMU 130, internal to the IMU 130, or somecombination thereof.

Based on the one or more measurement signals from one or more positionsensors 125, the IMU 130 generates fast calibration data indicating anestimated position of the VR headset 105 relative to an initial positionof the VR headset 105. For example, the position sensors 125 includemultiple accelerometers to measure translational motion (forward/back,up/down, left/right) and multiple gyroscopes to measure rotationalmotion (e.g., pitch, yaw, roll). In some embodiments, the IMU 130rapidly samples the measurement signals and calculates the estimatedposition of the VR headset 105 from the sampled data. For example, theIMU 130 integrates the measurement signals received from theaccelerometers over time to estimate a velocity vector and integratesthe velocity vector over time to determine an estimated position of areference point on the VR headset 105. Alternatively, the IMU 130provides the sampled measurement signals to the VR console 110, whichdetermines the fast calibration data. The reference point is a pointthat may be used to describe the position of the VR headset 105. Whilethe reference point may generally be defined as a point in space;however, in practice the reference point is defined as a point withinthe VR headset 105 (e.g., a center of the IMU 130).

The IMU 130 receives one or more calibration parameters from the VRconsole 110. As further discussed below, the one or more calibrationparameters are used to maintain tracking of the VR headset 105. Based ona received calibration parameter, the IMU 130 may adjust one or more IMUparameters (e.g., sample rate). In some embodiments, certain calibrationparameters cause the IMU 130 to update an initial position of thereference point so it corresponds to a next calibrated position of thereference point. Updating the initial position of the reference point asthe next calibrated position of the reference point helps reduceaccumulated error associated with the determined estimated position. Theaccumulated error, also referred to as drift error, causes the estimatedposition of the reference point to “drift” away from the actual positionof the reference point over time.

The imaging device 135 generates slow calibration data in accordancewith calibration parameters received from the VR console 110. Slowcalibration data includes one or more images showing observed positionsof the locators 120 that are detectable by the imaging device 135. Theimaging device 135 may include one or more cameras, one or more videocameras, any other device capable of capturing images including one ormore of the locators 120, or some combination thereof. Additionally, theimaging device 135 may include one or more filters (e.g., used toincrease signal to noise ratio). The imaging device 135 is configured todetect light emitted or reflected from locators 120 in a field of viewof the imaging device 135. In embodiments where the locators 120 includepassive elements (e.g., a retroreflector), the imaging device 135 mayinclude a light source that illuminates some or all of the locators 120,which retro-reflect the light towards the light source in the imagingdevice 135. Slow calibration data is communicated from the imagingdevice 135 to the VR console 110, and the imaging device 135 receivesone or more calibration parameters from the VR console 110 to adjust oneor more imaging parameters (e.g., focal length, focus, frame rate, ISO,sensor temperature, shutter speed, aperture, etc.).

The VR input interface 140 is a device that allows a user to send actionrequests to the VR console 110. An action request is a request toperform a particular action. For example, an action request may be tostart or end an application or to perform a particular action within theapplication. The VR input interface 140 may include one or more inputdevices. Example input devices include: a keyboard, a mouse, a gamecontroller, or any other suitable device for receiving action requestsand communicating the received action requests to the VR console 110. Anaction request received by the VR input interface 140 is communicated tothe VR console 110, which performs an action corresponding to the actionrequest. In some embodiments, the VR input interface 140 may providehaptic feedback to the user in accordance with instructions receivedfrom the VR console 110. For example, haptic feedback is provided whenan action request is received, or the VR console 110 communicatesinstructions to the VR input interface 140 causing the VR inputinterface 140 to generate haptic feedback when the VR console 110performs an action.

The VR console 110 provides media to the VR headset 105 for presentationto the user in accordance with information received from one or more of:the imaging device 135, the VR headset 105, and the VR input interface140. In the example shown in FIG. 1, the VR console 110 includes anapplication store 145, a tracking module 150, and a virtual reality (VR)engine 155. Some embodiments of the VR console 110 have differentmodules than those described in conjunction with FIG. 1. Similarly, thefunctions further described below may be distributed among components ofthe VR console 110 in a different manner than is described here.

The application store 145 stores one or more applications for executionby the VR console 110. An application is a group of instructions, thatwhen executed by a processor, generates content for presentation to theuser. Content generated by an application may be in response to inputsreceived from the user via movement of the HR headset 105 or the VRinterface device 140. Examples of applications include: gamingapplications, conferencing applications, video playback application, orother suitable applications.

The tracking module 150 calibrates the VR system 100 using one or morecalibration parameters and may adjust one or more calibration parametersto reduce error in determination of the position of the VR headset 105.For example, the tracking module 150 adjusts the focus of the imagingdevice 135 to obtain a more accurate position for observed locators onthe VR headset 105. Moreover, calibration performed by the trackingmodule 150 also accounts for information received from the IMU 130.Additionally, if tracking of the VR headset 105 is lost (e.g., theimaging device 135 loses line of sight of at least a threshold number ofthe locators 120), the tracking module 140 re-calibrates some or all ofthe system environment 100.

The tracking module 150 tracks movements of the VR headset 105 usingslow calibration information from the imaging device 135. The trackingmodule 150 determines positions of a reference point of the VR headset105 using observed locators from the slow calibration information and amodel of the VR headset 105. The tracking module 150 also determinespositions of a reference point of the VR headset 105 using positioninformation from the fast calibration information. Additionally, in someembodiments, the tracking module 150 may use portions of the fastcalibration information, the slow calibration information, or somecombination thereof, to predict a future location of the headset 105.The tracking module 150 provides the estimated or predicted futureposition of the VR headset 105 to the VR engine 155.

The VR engine 155 executes applications within the system environment100 and receives position information, acceleration information,velocity information, predicted future positions, or some combinationthereof of the VR headset 105 from the tracking module 150. Based on thereceived information, the VR engine 155 determines content to provide tothe VR headset 105 for presentation to the user. For example, if thereceived information indicates that the user has looked to the left, theVR engine 155 generates content for the VR headset 105 that mirrors theuser's movement in a virtual environment. Additionally, the VR engine155 performs an action within an application executing on the VR console110 in response to an action request received from the VR inputinterface 140 and provides feedback to the user that the action wasperformed. The provided feedback may be visual or audible feedback viathe VR headset 105 or haptic feedback via the VR input interface 140.

FIG. 2A is a diagram of a virtual reality (VR) headset, in accordancewith an embodiment. The VR headset 200 is an embodiment of the VRheadset 105, and includes a front rigid body 205 and a band 210. Thefront rigid body 205 includes one or more stacked electronic displayelements of the electronic display 115 (not shown in FIG. 2A), the IMU130, the one or more position sensors 125, and the locators 120. In theembodiment shown by FIG. 2A, the position sensors 125 are located withinthe IMU 130, and neither the IMU 130 nor the position sensors 125 arevisible to the user.

The locators 120 are located in fixed positions on the front rigid body205 relative to one another and relative to a reference point 215. Inthe example of FIG. 2A, the reference point 215 is located at the centerof the IMU 130. Each of the locators 120 emit light that is detectableby the imaging device 135. Locators 120, or portions of locators 120,are located on a front side 220A, a top side 220B, a bottom side 220C, aright side 220D, and a left side 220E of the front rigid body 205 in theexample of FIG. 2A.

FIG. 2B is a cross section 225 of the front rigid body 205 of theembodiment of a VR headset 200 shown in FIG. 2A. As shown in FIG. 2B,the front rigid body 205 includes an optical block 230 that providesaltered image light to an exit pupil 250. The exit pupil 250 is thelocation of the front rigid body 205 where a user's eye 245 ispositioned. For purposes of illustration, FIG. 2B shows a cross section225 associated with a single eye 245, but another optical block,separate from the optical block 230, provides altered image light toanother eye of the user.

The optical block 230 includes a stacked electronic display element 235of the electronic display 115, and the optics block 118. The stackedelectronic display element 235 emits image light toward the optics block118. The optics block 118 magnifies the image light, and in someembodiments, also corrects for one or more additional optical errors(e.g., distortion, astigmatism, etc.). The optics block 118 directs theimage light to the exit pupil 250 for presentation to the user.

FIG. 3 is an example stacked electronic display element 300 includingtwo display panels, in accordance with an embodiment. In someembodiments, the stacked electronic display element 300 is part of theelectronic display 115 of the VR headset 105 (e.g., stacked electronicdisplay element 235). In other embodiments it is some other electronicdisplay, e.g., a computer monitor, a television set, etc.

A stacked electronic display element 300 is a plurality of displaypanels that together output image light. The stacked electronic displayelement 300 includes a front electronic display panel 310 and a rearelectronic display panel 320. The front electronic display panel 310 isa transparent electronic display panel. As discussed above with respectto FIG. 1, a transparent electronic display panel may be, for example, aTOLED, some other transparent electronic display, or some combinationthereof. The rear electronic display panel may 320 may be, e.g., a LCD,an OLED, an AMOLED, a TOLED, some other display, or some combinationthereof.

While the stacked electronic display element 300 includes two electronicdisplay panels, in other embodiments, the stacked electronic displayelement 300 includes one or more intermediate components between thefront panel 310 and the rear panel 320. An intermediate component may bea transparent electronic display panel, a film (e.g., attenuator,polarizer, diffractive, spectral, etc.), or some combination thereof.

The front electronic display panel 310 includes an input surface 330(also referred to as a mounting surface) and an output surface 340 (alsoreferred to as a display surface). The rear electronic display panel 310includes an output surface 360 (also referred to as a display surface).The output surfaces 340, 360 each are configured to emit image light. Insome embodiments, the image light output by each panel may be a sameimage light, but have the brightness adjusted to account for attenuationof image light resulting from the image light passing through the frontpanel 310 and any intermediate components. In other embodiments, theimage light emitted from each electronic display panel may be differentfrom image light emitted from other electronic display panels (e.g., tocreate aggregate images of increased resolution, high dynamic range, 3-Dimages, or some combination thereof). In some embodiments, the frontelectronic display panel 310 is affixed to the rear electronic displayelement 320. For example, the input surface 330 of the front electronicdisplay panel 310 is affixed to the output surface 360 of the rearelectronic display element 320 using a transparent adhesive.Alternatively the front electronic display panel 310 may be affixed therear electronic display element 320 via a mechanical coupling.

Stacked Electronic Display Element Configured to Increase Fill Factor

FIG. 4A is an example array 400 of sub-pixel emission areas on a frontelectronic display panel (e.g., front electronic display panel 310) of astacked electronic display element (e.g., stacked electronic displayelement 300). In some embodiments, the array 400 may be part of astacked electronic display element of some other electronic display,e.g., a computer monitor, a television set, etc. The example array 400shown in FIG. 4A includes emission areas 410, 420, and 430 forrespectively, red sub-pixels, blue sub-pixels, and green sub-pixels. Theemission areas 410, 420, 430 correspond to areas of the sub-pixels thatactively emit light toward a viewing user. A non-emission area 440separates the emission areas of each sub-pixel from one or more adjacentemission areas of other sub-pixels. The non-emission area 440 is aportion of the array 400 that does not emit light, and in conventionalelectronic displays may become visible to a user under certaincircumstances (e.g., magnification), causing the screen door effect thatdegrades image quality.

FIG. 4B is an example array 450 of aggregate sub-pixel emission areas ona stacked electronic display panel (e.g., stacked electronic displayelement 300). In some embodiments, the array 450 may be part of someother electronic display, e.g., a computer monitor, a television set,etc. The example array 450 includes image light from the array 400 ofsub-pixel emission areas on a front electronic display panel (e.g.,front electronic display panel 310), as well as image light fromsub-pixel emission areas from a rear electronic display panel (e.g.,rear electronic display panel 320). The example array 450 shown in FIG.4A includes emission areas 410, 420, and 430 for respectively, redsub-pixels, blue sub-pixels, and green sub-pixels of the frontelectronic display panel, and emission areas 450, 460, and 470 forrespectively, red sub-pixels, blue sub-pixels, and green sub-pixels ofthe rear electronic display panel.

In FIG. 4B, the display panels are stacked such that the emission areasof the front electronic display panel are offset from the emission areasof the rear electronic display panel. The offset is such that imagelight emitted from the rear display panel passes through thenon-emission areas 440 of the front electronic display to generate theexample array 450. Accordingly, an effective area of emitted lightrelative to the total area of the sub-pixels is increased in the stackedelectronic display element, and thereby increases an effective fillfactor of the stacked electronic display element and reduces the screendoor effect. Moreover, in some embodiments, the front electronic displaypanel and the rear electronic display panel may be configured to emitimage light such that the aggregate image has a higher resolution than asingle electronic display element.

Stacked Electronic Display Element Configured for High Dynamic RangeOperation

Dynamic range describes a ratio between the maximum and minimum lightintensities in an image, and may vary from image to image. In practice,it is difficult to achieve the full dynamic range experienced by humansusing conventional electronic displays. Electronically reproducedimages/video often adjust image data having a wide dynamic range to fitinto a narrower recorded dynamic range that can be more easilydisplayed. For example, a scene showing an interior of a room with asunlit view outside a window, for instance, will have a relatively highdynamic range (e.g., approximately 100,000:1). However, a typical LCDdisplay has a dynamic range (e.g., commercially referred to as contrastratio meaning the full-on/full-off luminance ratio) of around 1000:1,accordingly, in some situations the LCD is not able to present theentire dynamic range. Instead, when showing a movie, game, etc., aconventional electronic display is able to show both shadowy nighttimescenes and bright outdoor sunlit scenes, but uses cues to suggest nightor day (e.g., a nighttime scene may usually contain duller colors, belit with blue lighting which reflects the way that the human eye seescolors at low light levels, etc.).

A HDR (High Dynamic Range) image stores pixel values that span a rangeof light intensities that is greater than a range able to be displayedby a single electronic display element. A stacked electronic displayelement maybe configured to present a HDR image that is the aggregate ofimage light emitted from the front electronic display panel, the rearelectronic display panel, and any additional display panels. The stackedelectronic display element assigns different luminosity ranges todifferent electronic display panels. For example, the stacked electronicdisplay may divide a total dynamic range of the HDR image into ‘n’number of reduced dynamic ranges, where ‘n’ corresponds to the number ofelectronic display panels in the stacked electronic display element. Areduced dynamic range is a dynamic range associated with a singledisplay panel (e.g., 1000:1). The stacked electronic display provideseach display panel its respective reduced dynamic range, and they eachdisplay panel in the stacked electronic display emits portions of animage in accordance with its associated reduced dynamic range.Accordingly, the dynamic range of the stacked electronic display elementscales with the number of electronic display panels within the stackedelectronic display. For example, in some embodiments the stackedelectronic display may contain three electronic displays, one of whichcould be configured to present high luminosity portions of an HDR image,another configured to present middle luminosity portions of the HDRimage, and the remaining electronic display panel configured to presentlow luminosity portions of the HDR image.

Additionally, in some embodiments, the stacked electronic displayelement may include additional intermediate comments between a frontelectronic display panel and a rear electronic display panel thataffect/enhance the image. For example, the stacked electronic displayelement may include one or more films (e.g., attenuator, polarizer,diffractive, spectral, etc.) between one or more electronic displaypanels.

FIG. 5 is an example array 500 of aggregate sub-pixel emission areas ona stacked electronic display element (e.g., stacked electronic displayelement 300) configured to operate as an HDR display. In someembodiments, the array 500 may be part of some other electronic display,e.g., a computer monitor, a television set, etc. The example array 500includes image light from an array of sub-pixel emission areas on a highluminosity electronic display panel (e.g., rear electronic display panel320), as well as image light from sub-pixel emission areas from a lowluminosity electronic display panel (e.g., front electronic displaypanel 310).

In this example, the stacked electronic display element includes twoelectronic display panels. One electronic display element presents lowluminosity portions of the HDR image, and the other electronic displaypanel presents high luminosity portions of the HDR image. In thisembodiment, high luminosity refers to a portion of the HDR image havinga higher luminosity than a low luminosity portion of the HDR image. Insome embodiments, the combination of the low luminosity and highluminosity portions of the image describe the luminosity of the entireHDR image.

The example array 500 shown in FIG. 5 includes emission areas 510, 520,and 530 for respectively, high luminosity red sub-pixels, highluminosity blue sub-pixels, and high luminosity green sub-pixels of thehigh luminosity electronic display panel, and emission areas 540, 550,and 560 for respectively, low luminosity red sub-pixels, low luminosityblue sub-pixels, and low luminosity green sub-pixels of the rearelectronic display panel. Accordingly, the array 500 is able to presentHDR images by effectively doubling the dynamic range that wouldotherwise be attributed to a single electronic display element.

In FIGS. 4A and 4B and 5, each panel has the same sub-pixel pattern. Inalternate embodiments, complimentary sub-pixel patterns may be used ondifferent display panels.

Stacked Electronic Display Element Configured for Presenting 3D Images

In some embodiments, the stacked electronic display element isconfigured to emit 3D images. As noted above, a typical electronicdisplay emits 2-dimensional images (e.g., ‘x’ and ‘y’ components in aCartesian coordinate system). In contrast a 3D image also includes depth(e.g., a range of ‘z’ values), which is not present in a 2-D image—wherea user simply focuses on a single plane.

In some embodiments, a stacked electronic display element (e.g., stackedelectronic display element 300) may be configured to present 3D images.For example, the stacked electronic display element may receive imagedata describing an image object for presentation to a user as a 3Dimage. The stacked electronic display element determines a total depthof the image object using the image data (e.g., determines a range of‘z’ that describes the image object). The stacked electronic displayelement then segments the determined total depth of the image objectinto ‘n’ different, successive, regions, where ‘n’ is a number ofelectronic display panels in the stacked electronic display element. Theregions are successive in the sense that n₁ describes a first portion ofthe image object, n₂ describes a next portion of the object, and so onfor all the regions. For example, if the image object was of an insideof a room that has a total depth of 12 feet and the stacked electronicdisplay element includes 6 electronic display elements, the stackedelectronic display element would segment the total depth into 6successive regions. Each region is associated with a range of depthvalues. For example, a first region (e.g., n₁) may be associated with z₁to z₂, a second region (e.g., n₂) would be associated with z₃ to z₄, andso on, where z₄≥z₃≥z₂≥z₁, and the absolute depth describes the size of aregion (i.e., |z₂−z₁|).

In some embodiments, an absolute depth of each region is the same. Forexample, an absolute depth for each region is the total depth divided bythe number of electronic display panels. Continuing the example above,as the total depth is 12 feet and the number of electronic displaypanels is 6, each region would have an absolute depth of 2 feet (=12/6)at successive positions throughout the total depth of the image object.Alternatively, the absolute depth of one or more of the regions maydiffer from each other. For example, the stacked electronic displayelement may segment the image object such that some regions are muchlarger than others. For example, if the image object is of a room thatonly includes a flower in the foreground, the stacked electronic displayelement may segment an image object such that the absolute depth of theregions are smaller over the region describing the flower (i.e., moreregions are describing the foreground), and larger for regionsdescribing the background.

The stacked electronic display element assigns the regions to each ofthe electronic display panels, and the stacked electronic display panelsemit image light corresponding, respectively, to their assigned region.Accordingly, each electronic display panel is emitting image lightrepresentative of particular slice of the image object over a range ofdepth values corresponding to its assigned region. Note, because eachelectronic display panel is emitting image light representative of asingle region, energy consumption is generally comparable to energyconsumption of a single electronic display panel presenting the entireimage object.

As the electronic display panels do not occupy the same location, anaggregate image emitted by the stacked electronic display element hasdepth (i.e., the aggregate image being a 3-D image). A user could thenfocus throughout the 3D image rather than on a single image plane aswould be typical in a conventional 2D display. Additionally, in someembodiments, the spacing between the electronic display panels may beincreased to, e.g., better emphasize differences in depth between lightemitted from different electronic display panels. For example, glassthicknesses may be increased on one or more of the electronic displayelements, film thicknesses between electronic display panels increased,etc. Additionally, in some embodiments, a user may elect to have thestacked electronic display element present a “flat” 2D image. Adifference from conventional 2D displays is that the stacked electronicdisplay element may display an image using different panels—which can beused to increase the viewing comfort of a viewing user. For example, aviewing user watching a movie may instruct the stacked electronicdisplay element to adjust the distance that the image appears from theviewing user to increase their viewing comfort of the movie.

FIG. 6A is a perspective view of an example an image object 600,according to an embodiment. The image object 600 is representative of anopaque 3D object to be presented by a stacked electronic displayelement. The image object 600 includes a cross section 610 whichrepresents a slice in y-z plane of the image object 600. FIG. 6B is across section 620 of the image object 600 in FIG. 6A, according to anembodiment.

FIG. 6C is a diagram 625 including a stacked electronic display element630 configured to operate as a 3D display, according to an embodiment.In some embodiments, the stacked electronic display element 630 is partof the electronic display 115 of the VR headset 105 (e.g., stackedelectronic display element 235). In other embodiments it is some otherelectronic display, e.g., a computer monitor, a television set, etc.

In this example, the stacked electronic element 630 includes sixelectronic display panels, specifically, electronic display panels 660A,660B, 660C, 660D, 660E, and 660F. In some embodiments, the spacingbetween one or more of the electronic display panels 660 may vary tohelp emphasize a difference in depth in image light emitted fromdifferent electronic display panels 660. The stacked electronic displayelement 630 segments the image object 600 into 6 different segments. Inthis embodiment, each of regions has a same absolute depth.

Each of the electronic display panels 660A, 660B, 660C, 660D, 660E, and660F emit image light corresponding to their assigned region. Forexample, the electronic display panel 660F emits image lightrepresentative of a top portion 670 and bottom portion 675 of the imageobject 600, accordingly the electronic display panel 660F does notpresent portions of the image object 600 that are assigned to differentregion (e.g., a tip 680 of the image object 600 that is emitted by theelectronic display panel 660A). This partial usage of each electronicdisplay element 660 helps minimize power consumption—such that totalpower consumption is comparable to a single electronic display element660 presenting the entire image object 660.

The stacked electronic display element 630 is positioned inside a focuspoint 635 of the optics block 118. The optics block 118 has an effectivefocal length which is positive, accordingly, the stacked electronicstacked electronic display element 630 positioned inside the focus point635 results in an aggregate image 665 that is virtual, erect, andappears farther away from an eye 245 of a user than the electronicdisplay element 630. Note, as drawn in FIG. 6C, the portion of the imageobject 600 shown in the aggregate image 655 corresponds to the crosssection 610 shown in FIGS. 6A, and 6B. However, this is merely an crosssection of the total image, and if illustrated in its entirety theaggregate image 655 is a 3-D image of the image object 600.

Additional Configuration Information

The foregoing description of the embodiments has been presented for thepurpose of illustration; it is not intended to be exhaustive or to limitthe patent rights to the precise forms disclosed. Persons skilled in therelevant art can appreciate that many modifications and variations arepossible in light of the above disclosure.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the patent rights be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thepatent rights, which is set forth in the following claims.

What is claimed is:
 1. A head-mounted display (HMD) comprising: anelectronic display element comprising a plurality of display panels thattogether output image light, the plurality of panels including a firstdisplay panel and a second display panel, the first display panelincluding a first plurality of sub-pixels, the first plurality ofsub-pixels separated from each other by a non-emission area, the seconddisplay panel including a second plurality of sub-pixels, the seconddisplay panel positioned offset from the first display panel such thatthe second plurality of sub-pixels emit light through the non-emissionarea of the first display panel, wherein the first plurality ofsub-pixels are configured to operate over a first range of luminosities,and the second plurality of sub-pixels are configured to operate over asecond range of luminosities that is higher than the first range ofluminosities, and the electronic display element is configured to:receive an image having a dynamic range; divide the dynamic range into“n” number of reduced dynamic ranges, wherein “n” is a number of displaypanels, and each reduced dynamic range corresponds to a different rangeof luminosities that different display panels are configured to operateover; provide each display panel a respective reduced dynamic range;display, by the first display panel, a first portion of the image inaccordance with the first range of luminosities and a first reduceddynamic range; display, by the second display panel, a second portion ofimage in accordance with the second range of luminosities and a secondreduced dynamic range; and an optics block configured to direct theimage light to an exit pupil of the HMD corresponding to a location ofan eye of a user of the HMD.
 2. The HMD of claim 1, wherein thedisplayed first portion of the image and the displayed second portion ofthe image have a total contrast ratio that is at least 100,000:1.
 3. TheHMD of claim 1, wherein the electronic display panel further comprises athird display panel, the third display panel including a third pluralityof sub-pixels, the third display panel positioned offset from the firstdisplay panel and the second display panel such that the third pluralityof sub-pixels emit light through the non-emission area of the firstdisplay panel and the non-emission area of the second display panel, andthe third plurality of sub-pixels operate over a third range ofluminosities that is higher than the second range of luminosities, andthe electronic display element is configured to: display, by the thirddisplay panel, a third portion of the image in accordance with the thirdrange of luminosities and a third reduced dynamic range.
 4. The HMD ofclaim 1, wherein the first display panel and the second display panelare partially transparent to visible light.
 5. The HIVID of claim 4,wherein the electronic display element is configured to: receive imagedata describing an image object for presentation to a user as a 3Dimage; determine a total depth of the image object using the image data;segment the determined total depth of the image object into “n”different, successive, regions; assign the regions to each of theelectronic display panels, wherein a first region is assigned to thefirst display panel and a second region is assigned to the seconddisplay panel; display, by the first display panel, the first region ofthe image; and display, by the second display panel, the second regionof the image.
 6. The HMD of claim 5, wherein each region has a samevalue of absolute depth, the absolute depth being the total depth of theimage divided by “n.”
 7. The HMD of claim 5, wherein the first region isassociated with a first depth and the second region is associated with asecond depth that is different than the first depth.
 8. The HMD of claim1, wherein the electronic display panel further comprises anintermediate component, the intermediate component positioned betweenthe first display panel and the second display panel such that lightemitted from the second display panel passes through the intermediatecomponent before passing through the first display panel.
 9. The HMD ofclaim 8, wherein the intermediate component is selected from a groupconsisting of: a transparent electronic display panel, an attenuator, apolarizer, and diffractive element.
 10. The HMD of claim 8, wherein aspacing between the intermediate component and the second display panelis different than a spacing between first display panel and the seconddisplay panel.
 11. The HMD of claim 8, wherein the second display panelis opaque to the light emitted from the second plurality of pixels andthe intermediate component and the first display panel are both at leastpartially transparent to the light emitted from the second plurality ofpixels.
 12. A head-mounted display (HMD) comprising: an electronicdisplay element comprising a plurality of display panels that togetheroutput image light, the plurality of panels including a first displaypanel and a second display panel, the first display panel including afirst plurality of sub-pixels, the first plurality of sub-pixelsseparated from each other by a non-emission area, the second displaypanel including a second plurality of sub-pixels, the second displaypanel positioned offset from the first display panel such that thesecond plurality of sub-pixels emit light through the non-emission areaof the first display panel, wherein the first plurality of sub-pixelsare configured to operate over a first range of luminosities, and thesecond plurality of sub-pixels are configured to operate over a secondrange of luminosities that is higher than the first range ofluminosities, and the electronic display element is configured to:receive an image having a dynamic range; divide the dynamic range into“n” number of reduced dynamic ranges, wherein “n” is a number of displaypanels, and each reduced dynamic range corresponds to a different rangeof luminosities that different display panels are configured to operateover; provide each display panel a respective reduced dynamic range;display, by the first display panel, a first portion of the image inaccordance with the first range of luminosities and a first reduceddynamic range; display, by the second display panel, a second portion ofimage in accordance with the second range of luminosities and a secondreduced dynamic range; and an optics block configured to: magnify theimage light; and direct the image light to an exit pupil of the HMDcorresponding to a location of an eye of a user of the HMD.
 13. The HMDof claim 12, wherein the electronic display panel further comprises athird display panel, the third display panel including a third pluralityof sub-pixels, the third display panel positioned offset from the firstdisplay panel and the second display panel such that the third pluralityof sub-pixels emit light through the non-emission area of the firstdisplay panel and the non-emission area of the second display panel, andthe third plurality of sub-pixels operate over a third range ofluminosities that is higher than the second range of luminosities, andthe electronic display element is configured to: display, by the thirddisplay panel, a third portion of the image in accordance with the thirdrange of luminosities and a third reduced dynamic range.
 14. The HMD ofclaim 13, wherein the first display panel and the second display panelare partially transparent to visible light.
 15. The HMD of claim 14,wherein the electronic display element is configured to: receive imagedata describing an image object for presentation to a user as a 3Dimage; determine a total depth of the image object using the image data;segment the determined total depth of the image object into “n”different, successive, regions; assign the regions to each of theelectronic display panels, wherein a first region is assigned to thefirst display panel and a second region is assigned to the seconddisplay panel; display, by the first display panel, the first region ofthe image; and display, by the second display panel, the second regionof the image.
 16. The HMD of claim 12, wherein the electronic displaypanel further comprises an intermediate component, the intermediatecomponent positioned between the first display panel and the seconddisplay panel such that light emitted from the second display panelpasses through the intermediate component before passing through thefirst display panel.
 17. A head-mounted display (HMD) comprising: anelectronic display element comprising a plurality of display panels thattogether output image light, the plurality of panels including a firstdisplay panel and a second display panel, the first display panelincluding a first plurality of sub-pixels, the first plurality ofsub-pixels separated from each other by a non-emission area, the seconddisplay panel including a second plurality of sub-pixels, the seconddisplay panel positioned offset from the first display panel such thatthe second plurality of sub-pixels emit light through the non-emissionarea of the first display panel, wherein the first plurality ofsub-pixels are configured to operate over a first range of luminosities,and the second plurality of sub-pixels are configured to operate over asecond range of luminosities that is higher than the first range ofluminosities, and the electronic display element is configured to:receive an image having a dynamic range; divide the dynamic range into“n” number of reduced dynamic ranges, wherein “n” is a number of displaypanels, and each reduced dynamic range corresponds to a different rangeof luminosities that different display panels are configured to operateover; provide each display panel a respective reduced dynamic range;display, by the first display panel, a first portion of the image inaccordance with the first range of luminosities and a first reduceddynamic range; display, by the second display panel, a second portion ofimage in accordance with the second range of luminosities and a secondreduced dynamic range; and an optics block configured to: correct one ormore optical aberrations in the image light; magnify the image light;and direct the image light to an exit pupil of the HMD corresponding toa location of an eye of a user of the HMD.